Compounds containing silicon-containing groups, medical devices, and methods

ABSTRACT

Compounds that include silicon-containing groups, and optionally urethane groups, urea groups, or combinations thereof (i.e., polyurethanes, polyureas, or polyurethane-ureas), as well as materials and methods for making such compounds.

FIELD OF THE INVENTION

[0001] This invention relates to compounds containing silicon-containinggroups, preferably such compounds are polymers containing urethaneand/or urea groups, particularly elastomers. Such materials areparticularly useful as biomaterials in medical devices.

BACKGROUND OF THE INVENTION

[0002] The chemistry of polyurethanes and/or polyureas is extensive andwell developed. Typically, polyurethanes and/or polyureas are made by aprocess in which a polyisocyanate is reacted with a molecule having atleast two functional groups reactive with the polyisocyanate, such as apolyol or polyamine. The resulting polymer can be further reacted with achain extender, such as a diol or diamine, for example. The polyol orpolyamine is typically a polyester, polyether, or polycarbonate polyolor polyamine, for example.

[0003] Polyurethanes and/or polyureas can be tailored to produce a rangeof products from soft and flexible to hard and rigid. They can beextruded, injection molded, compression molded, and solution spun, forexample. Thus, polyurethanes and polyureas, particularly polyurethanes,are important biomedical polymers, and are used in implantable devicessuch as artificial hearts, cardiovascular catheters, pacemaker leadinsulation, etc.

[0004] Commercially available polyurethanes used for implantableapplications include BIOSPAN segmented polyurethanes, manufactured byPolymer Technology Group of Berkeley, Calif., PELLETHANE segmentedpolyurethanes, sold by Dow Chemical, Midland, Mich., and TECOFLEXsegmented polyurethanes sold by Thermedics, Inc., Woburn, Mass.

[0005] Polyurethanes are described in the article “Biomedical Uses ofPolyurethanes,” by Coury et al., in Advances in Urethane Science andTechnology, 9, 130-168, edited by Kurt C. Frisch and Daniel Klempner,Technomic Publishing Co., Lancaster, Pa. (1984). Typically, polyetherpolyurethanes exhibit more biostability than polyester polyurethanes andpolycarbonate polyurethanes, as these are more susceptible tohydrolysis. Thus, polyether polyurethanes are generally preferredbiopolymers.

[0006] Polyether polyurethane elastomers, such as PELLETHANE 2363-80A(P80A) and 2363-55D (P55D), which are prepared from polytetramethyleneether glycol (PTMEG) and methylene bis(diisocyanatobenzene) (MDI)extended with 1,4-butanediol, are widely used for implantable cardiacpacing leads. Pacing leads are electrodes that carry stimuli to tissuesand biologic signals back to implanted pulse generators. The use ofpolyether polyurethane elastomers as insulation on such leads hasprovided significant advantage over silicone rubber, primarily becauseof the higher tensile strength of the polyurethanes.

[0007] There is some problem, however, with biodegradation of polyetherpolyurethane insulation, which can cause failure. Polyetherpolyurethanes are susceptible to oxidation in the body, particularly inareas that are under stress. When oxidized, polyether polyurethaneelastomers can lose strength and can form cracks, which might eventuallybreach the insulation. This, thereby, can allow bodily fluids to enterthe lead and form a short between the lead wire and the implantablepulse generator (IPG). It is believed that the ether linkages degrade,perhaps due to metal ion catalyzed oxidative attack at stress points inthe material.

[0008] One approach to solving this problem has been to coat theconductive wire of the lead. Another approach has been to add anantioxidant to the polyurethane. Yet another approach has been todevelop new polyurethanes that are more resistant to oxidative attack.Such polyurethanes include only segments that are resistant to metalinduced oxidation, such as hydrocarbon- and carbonate-containingsegments. For example, polyurethanes that are substantially free ofether and ester linkages have been developed. This includes thesegmented aliphatic polyurethanes of U.S. Pat. No. 4,873,308 (Coury etal.). Another approach has been to include a sacrificial moiety(preferably in the polymer backbone) that preferentially oxidizesrelative to all other moieties in the polymer, which upon oxidationprovides increased tensile strength relative to the polymer prior tooxidation. This is disclosed in U.S. Pat. No. 5,986,034 (DiDomenico etal.), U.S. Pat. No. 6,111,052 (DiDomenico et al.), and U.S. Pat. No.6,149,678 (DiDomenico et al.).

[0009] Although such materials produce more stable implantable devicesthan polyether polyurethanes, there is still a need for biostablepolymers, particularly polyurethanes suitable for use as insulation onpacing leads.

SUMMARY OF THE INVENTION

[0010] The present invention relates to compounds, preferably polymers,that include silicon-containing groups. The silicon-containing groupsare typically silane- and/or siloxane-containing groups. Particularlypreferred polymers include urethane groups, urea groups, or combinationsthereof (i.e., polyurethanes, polyureas, or polyurethane-ureas).Polymers of the present invention may be random, alternating, block,star block, segmented, or combinations thereof. Preferably, the polymeris a segmented polyurethane. Certain embodiments of the polymers of thepresent invention can be used as biomaterials in medical devices.Preferred polymers are also preferably substantially free of ester,ether, and carbonate linkages.

[0011] The present invention also provides a polymer, and a medicaldevice that incorporates such polymer, wherein the polymer is preparedfrom a compound (typically a polymeric starting material) of the formula(Formula I):

Y—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—Y

[0012] wherein: each Y is independently OH or NR⁴H; n=2 or more; each R¹is independently a straight chain or branched alkylene group (typicallyreferred to as a divalent saturated aliphatic group) optionallyincluding heteroatoms; each R² is independently a saturated orunsaturated aliphatic group, an aromatic group, or combinations thereof,optionally including heteroatoms (typically referred to as a monovalentgroup); Z is oxygen or R³ wherein each R³ is independently a straightchain alkylene group, a phenylene group, or a straight chain or branchedalkyl substituted phenylene group, wherein each R³ optionally includesheteroatoms; and each R⁴ is independently H or a saturated orunsaturated aliphatic group, an aromatic group, or combinations thereof;with the proviso that at least one of the Z groups is oxygen and atleast one of the Z groups is R³ (preferably, every other Z is oxygen);and with the proviso that R¹ does not include urethane groups when Y isOH (although R¹ does become part of urethane linkages).

[0013] Polymers of the present invention thereby include groups of theformula (Formula II):

—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—

[0014] wherein Y, n, R¹, R², Z, and R⁴ are as defined herein.

[0015] Also provided is a compound of the formula (Formula I):

Y—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—Y

[0016] wherein: each Y is independently OH or NR⁴H; n=2 or more; each R¹is independently a straight chain or branched alkylene group optionallyincluding heteroatoms; each R² is independently a saturated orunsaturated aliphatic group, an aromatic group, or combinations thereof,optionally including heteroatoms; Z is oxygen or R³, wherein each R³ isindependently a straight chain alkylene group, a phenylene group, or astraight chain or branched alkyl substituted phenylene group, whereineach R³ optionally includes heteroatoms; and each R⁴ is independently Hor a saturated or unsaturated aliphatic group, an aromatic group, orcombinations thereof; with the proviso that at least one of the Z groupsis oxygen and at least one of the Z groups is R³ (preferably, everyother Z is oxygen); and with the proviso that R¹ does not includeurethane groups.

[0017] It should be understood that in the above formulas, the repeatunit -Z-Si(R²)₂— can vary within any one molecule. That is, in additionto each of the R² groups being the same or different within each Si(R²)₂group, each of the -Z-Si(R²)₂— groups can be the same or different inany one molecule.

[0018] As written, the formulas provided herein (for both the resultantpolymers and the polymeric starting materials) encompass alternating,random, block, star block, segmented copolymers, and combinationsthereof (e.g., wherein certain portions of the molecule are alternatingand certain portions are random). With respect to star block copolymers,it should be understood that the polymeric segments described hereincould form at least a part of one or more arms of the star, although thesegment itself would not necessarily include the core branch point ofthe star.

[0019] Methods of preparation of such polymers and compounds are alsoprovided. In one embodiment of making a segmented polymer, the methodincludes combining a polyisocyanate with a compound of Formula I.

[0020] As used herein, the terms “a,” “an,” “one or more,” and “at leastone” are used interchangeably.

[0021] As used herein, the term “aliphatic group” means a saturated orunsaturated linear (i.e., straight chain), cyclic (i.e.,cycloaliphatic), or branched organic hydrocarbon group. This term isused to encompass alkyl (e.g., —CH₃, which is considered a “monovalent”group) (or alkylene if within a chain such as —CH₂—, which is considereda “divalent” group), alkenyl (or alkenylene if within a chain), andalkynyl (or alkynylene if within a chain) groups, for example. The term“alkyl group” means a saturated linear or branched hydrocarbon groupincluding, for example, methyl, ethyl, isopropyl, t-butyl, heptyl,dodecyl, octadecyl, amyl, 2-ethylhexyl, and the like. The term “alkenylgroup” means an unsaturated, linear or branched hydrocarbon group withone or more carbon-carbon double bonds, such as a vinyl group. The term“alkynyl group” means an unsaturated, linear or branched hydrocarbongroup with one or more carbon-carbon triple bonds. The term “aromaticgroup” or “aryl group” means a mono- or polynuclear aromatic organichydrocarbon group. These hydrocarbon groups may be substituted withheteroatoms, which can be in the form of functional groups. The term“heteroatom” means an element other than carbon (e.g., nitrogen, oxygen,sulfur, chlorine, etc.).

[0022] As used herein, a “biomaterial” may be defined as a material thatis substantially insoluble in body fluids and tissues and that isdesigned and constructed to be placed in or onto the body or to contactfluid or tissue of the body. Ideally, a biomaterial will not induceundesirable reactions in the body such as blood clotting, tissue death,tumor formation, allergic reaction, foreign body reaction (rejection) orinflammatory reaction; will have the physical properties such asstrength, elasticity, permeability and flexibility required to functionfor the intended purpose; can be purified, fabricated and sterilizedeasily; and will substantially maintain its physical properties andfunction during the time that it remains implanted in or in contact withthe body. A “biostable” material is one that is not broken down by thebody, whereas a “biocompatible” material is one that is not rejected bythe body.

[0023] As used herein, a “medical device” may be defined as a devicethat has surfaces that contact blood or other bodily tissues in thecourse of their operation. This can include, for example, extracorporealdevices for use in surgery such as blood oxygenators, blood pumps, bloodsensors, tubing used to carry blood and the like which contact bloodwhich is then returned to the patient. This can also include implantabledevices such as vascular grafts, stents, electrical stimulation leads,heart valves, orthopedic devices, catheters, shunts, sensors,replacement devices for nucleus pulposus, cochlear or middle earimplants, intraocular lenses, and the like.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS OF THE INVENTION

[0024] The present invention provides polymers (preferably, segmentedpolyurethanes), compounds used to prepare such polymers (preferably,these form the soft segments of segmented polymers), and medical devicesthat include such polymers (preferably, biomaterials). Preferably, thepolymers are generally resistant to oxidation and/or hydrolysis,particularly with respect to their backbones, as opposed to their sidechains.

[0025] The polymers include one or more silicon-containing groups. Thesesilicon-containing groups are of the formula -Z-Si(R²)₂— wherein Z isoxygen (thereby forming a siloxane group) or is R³ (thereby forming asilane group). Each R³ may be the same or different (i.e., isindependently) and is a straight chain alkylene group, a phenylenegroup, or a straight chain or branched alkyl substituted pheylene group,wherein each R³ optionally includes heteroatoms (which may be in thechain of the organic group or pendant therefrom as in a functionalgroup). In any one compound, at least one of the Z groups is oxygen andat least one of the Z groups is an R³ group. For certain embodiments,the Z groups are alternating with every “even” numbered Z group being anoxygen (i.e., every other Z is oxygen).

[0026] Polymers of the present invention are prepared from a compound ofthe formula (Formula I):

Y—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—Y

[0027] wherein: each Y is independently OH or NR⁴H; n=2 or more; each R¹is independently a straight chain or branched alkylene group optionallyincluding heteroatoms; each R² is independently a saturated orunsaturated aliphatic group, an aromatic group, or combinations thereof,optionally including heteroatoms; Z is as defined above; and each R⁴ isindependently H or a saturated or unsaturated aliphatic group, anaromatic group, or combinations thereof.

[0028] Polymers of the present invention thereby include groups of theformula (Formula II):

—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—

[0029] wherein n, R¹, R², and Z are as defined herein.

[0030] Polymers of the present invention can be used in medical devicesas well as nonmedical devices. Preferably, they are used in medicaldevices and are suitable as biomaterials. Examples of medical devicesare listed above. Examples of nonmedical devices include foams,insulation, clothing, footwear, paints, coatings, adhesives, buildingconstruction materials, etc.

[0031] The polymers suitable for forming biomaterials for use in medicaldevices according to the present invention include silicon-containinggroups, and are preferably polyurethanes, polyureas, orpolyurethane-ureas. These polymers can vary from hard and rigid to softand flexible. Preferably, the polymers are elastomers. An “elastomer” isa polymer that is capable of being stretched to approximately twice itsoriginal length and retracting to approximately its original length uponrelease.

[0032] Polymers of the present invention can be or copolymers, althoughpreferably, they are random, alternating, block, star block, segmentedcopolymers, or combinations thereof. Most preferably, the polymers aresegmented copolymers (i.e., containing a multiplicity of both hard andsoft domains or segments on any polymer chain) and are comprisedsubstantially of alternating relatively soft segments and relativelyhard segments.

[0033] For segmented polymers, either the hard or the soft segments, orboth, can include a silicon-containing moiety, thereby providing apolymer that has reduced susceptibility to oxidation and/or hydrolysis,at least with respect to the polymer backbone. As used herein, a “hard”segment is one that is either crystalline at use temperature oramorphous with a glass transition temperature above use temperature(i.e., glassy), and a “soft” segment is one that is amorphous with aglass transition temperature below use temperature (i.e., rubbery). Acrystalline or glassy moiety or hard segment is one that addsconsiderable strength and higher modulus to the polymer. Similarly, arubbery moiety or soft segment is one that adds flexibility and lowermodulus, but may add strength particularly if it undergoes straincrystallization, for example. The random or alternating soft and hardsegments are linked by urethane and/or urea groups and the polymers maybe terminated by hydroxyl, amine, and/or isocyanate groups.

[0034] As used herein, a “crystalline” material or segment is one thathas ordered domains. A “noncrystalline” material or segment is one thatis amorphous (a noncrystalline material may be glassy or rubbery). A“strain crystallizing” material is one that forms ordered domains when astrain or mechanical force is applied.

[0035] An example of a medical device for which the polymers areparticularly well suited is a medical electrical lead, such as a cardiacpacing lead, a neurostimulation lead, etc. Examples of such leads aredisclosed, for example, in U.S. Pat. No. 5,040,544 (Lessar et al.), U.S.Pat. No. 5,375,609 (Molacek et al.), U.S. Pat. No. 5,480,421 (Otten),and U.S. Pat. No. 5,238,006 (Markowitz).

[0036] Polymers and Methods of Preparation

[0037] A wide variety of polymers are provided by the present invention.They can be or random, alternating, block, star block, segmentedcopolymers (or combinations thereof, preferably they are copolymers(including terpolymers, tetrapolymers), that can include olefins,amides, esters, imides, epoxies, ureas, urethanes, carbonates, sulfones,ethers, acetals, phosphonates, and the like. These includesilicon-containing groups of the formula —O—Si(R²)₂— (siloxane groups)or —R³—Si(R²)₂— (silane groups). Such polymers can be prepared using avariety of techniques from polymerizable compounds (e.g., monomers,oligomers, or polymers) containing such silicon-containing groups. Suchcompounds include dienes, diols, diamines, or combinations thereof, forexample.

[0038] Although certain preferred polymers are described herein, thepolymers used to form the preferred biomaterials in the medical devicesof the present invention can be a wide variety of polymers that includeurethane groups, urea groups, or combinations thereof. Such polymers areprepared from isocyanate-containing compounds, such as polyisocyanates(preferably diisocyanates) and compounds having at least two functionalgroups reactive with the isocyanate groups, such as polyols and/orpolyamines (preferably diols and/or diamines). Any of these reactantscan include a silicon-containing group (preferably in the polymerbackbone), although preferably a silicon-containing moiety is providedby the diols and/or diamines of Formula I.

[0039] The presence of the silicon-containing moiety provides a polymerthat is typically more resistant to oxidative and/or hydrolyticdegradation but still has a relatively low glass transition temperature(Tg). Furthermore, preferably, both the hard and soft segments arethemselves substantially ether-free, ester-free, and carbonate-freepolyurethanes, polyureas, or combinations thereof. As stated above, thesilicon-containing groups are of the formula -Z-Si(R²)₂— wherein Z isoxygen (thereby forming a siloxane group) or is R³ (thereby forming asilane group).

[0040] In one embodiment, particularly preferred polymers also includeone or more urethane groups, urea groups, or combinations thereof(preferably, just urethane groups). In another embodiment, particularlypreferred polymers are copolymers (i.e., prepared from two or moremonomers, including terpolymers or tetrapolymers). Thus, the presentinvention provides polymers with the silicon-containing groups randomlydistributed or ordered in blocks or segments.

[0041] Polymers of the present invention can be linear, branched, orcrosslinked. This can be done using polyfunctional isocyanates orpolyols (e.g., diols, triols, etc.) or using compounds havingunsaturation or other functional groups (e.g., thiols) in one or moremonomers with radiation crosslinking. Such methods are well known tothose of skill in the art.

[0042] Preferably, such polymers (and the compounds used to make them)have substantially no tertiary carbons in the main chain (i.e.,backbone).

[0043] A preferred source of the group of the formula—[—(R¹)_(n)—(-Z-(R²)_(m)—)_(p)—(—Si(R)₂—V_(r)—)_(s)—]_(q)— is a compound(typically a polymeric starting compound) of the formula (Formula I):

Y—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—Y

[0044] wherein: each Y is independently OH or NR⁴H; n=2 or more; each R¹is independently a straight chain or branched alkylene group optionallyincluding heteroatoms; each R² is independently a saturated orunsaturated aliphatic group, an aromatic group, or combinations thereof,optionally including heteroatoms; Z is oxygen or R³, wherein each R³ isindependently a straight chain alkylene group, a phenylene group, or astraight chain or branched alkyl substituted phenylene group, whereineach R³ optionally includes heteroatoms; and each R⁴ is independently Hor a saturated or unsaturated aliphatic group, an aromatic group, orcombinations thereof; with the proviso that at least one of the Z groupsis oxygen and at least one of the Z groups is R³; and with the provisothat R¹ does not include urethane groups when Y is OH.

[0045] It should be understood that in Formula I, the repeat unit-Z-Si(R²)₂-can vary within any one molecule. That is, in addition toeach of the R² groups being the same or different within each Si(R²)₂group, the -Z-Si(R²)₂-groups can be the same or different in any onemolecule. The value for “n” is an average value. Preferably, n is 1 to50, and more preferably, n is 1 to 20.

[0046] The R¹, R², and R³ groups are selected such that the numberaverage molecular weight of a polymeric starting material of the presentinvention is preferably no greater than about 100,000 grams per mole(g/mol or Daltons), more preferably, no greater than about 5000 g/mol,and most preferably no greater than about 1500 g/mol. Preferably, thenumber average molecular weight of the polymeric starting material is atleast about 500 g/mol.

[0047] The number average molecular weight of the resultant polymer(without crosslinking) of the present invention is preferably no greaterthan about 100,000,000 g/mol, which is desirable for melt processing ofthe polymer More preferably, the number average molecular weight of theresultant polymer (without crosslinking) of the present invention is nogreater than about 500,000 g/mol. Preferably, the number averagemolecular weight of the polymer (without crosslinking) is at least about20,000 g/mol.

[0048] Each R¹ is independently a straight chain or branched alkylenegroup (i.e., a divalent saturated aliphatic group) optionally includingheteroatoms, such as nitrogen, oxygen, phosphorus, sulfur, and halogen.The heteroatoms can be in the backbone of the polymer or pendanttherefrom, and they can form functional groups (e.g., carbonyl).Preferably, R¹ does not include heteroatoms. More preferably, each R¹ isindependently a straight chain or branched alkylene group includes 20carbon atoms or less. Most preferably, each R¹ is independently astraight chain or branched (C3-C20)alkylene group.

[0049] The R² groups on the silicon atoms are selected such that theultimate product (e.g., a segmented polyurethane polymer) has thefollowing properties relative to a polymer without thesilicon-containing groups: greater chain flexibility; lesssusceptibility to oxidation and hydrolysis; and/or greater ability tomodify the polymers using functional groups within the R groups.

[0050] Although the silicon-containing groups reduce the susceptibilityof the polymeric starting material and the ultimate polymer to oxidationor hydrolysis, the R² groups could themselves be susceptible tooxidation or hydrolysis as long as the main chain (i.e., the backbone)is not generally susceptible to such reactions.

[0051] Each R² is independently a monovalent saturated or unsaturatedaliphatic group, an aromatic group, or combinations thereof, optionallyincluding heteroatoms. Preferably, the R² groups are each independentlyan alkyl group, an aryl group, or combinations thereof. More preferably,the R² groups are each independently an alkyl group, a phenyl group, oran alkyl substituted phenyl group. Even more preferably, the R² groupsare each independently a straight chain or branched alkyl group(preferably having 20 carbon atoms or less), a phenyl group, or astraight chain or branched alkyl substituted phenyl group (preferablyhaving 20 carbon atoms or less, and more preferably 6 carbon atoms orless, in the alkyl substituent). Most preferably, the R² groups are eachindependently a straight chain or branched (C1-C3)alkyl group(preferably without heteroatoms).

[0052] Optionally, the R² groups can include heteroatoms, such asnitrogen, oxygen, phosphorus, sulfur, and halogen. These could be in thechain of the organic group or pendant therefrom in the form offunctional groups, as long as the polymer is generally resistant tooxidation and/or hydrolysis, particularly with respect to its backbone,as opposed to its side chains. Such heteroatom-containing groups (e.g.,functional groups) include, for example, an alcohol, ether, acetoxy,ester, aldehyde, acrylate, amine, amide, imine, imide, and nitrile,whether they be protected or unprotected.

[0053] Each R³ is independently a straight chain alkylene group, aphenylene group, or a straight chain or branched alkyl substitutedphenylene group, wherein each R³ group optionally includes heteroatoms.Preferably, each R³ is independently a straight chain alkylene group.Preferably, R³ does not include heteroatoms. More preferably, each R³group includes 20 carbon atoms or less, even more preferably 12 carbonatoms or less, and most preferably 10 carbon atoms or less. Morepreferably, each R³ group includes at least 1 carbon atom, morepreferably, at least 4 carbon atoms, and most preferably at least 6carbon atoms. Alternatively, each alkyl substituent on the phenylenegroup independently and preferably includes 20 carbon atoms or less,even more preferably 12 carbon atoms or less, and most preferably 10carbon atoms or less. More preferably, each alkyl substituent on thephenylene group independently and preferably includes at least 1 carbonatom, more preferably, at least 4 carbon atoms, and most preferably atleast 6 carbon atoms.

[0054] Each R⁴ is independently H or a saturated or unsaturatedaliphatic group, an aromatic group, or combinations thereof. Preferably,each R⁴ is independently hydrogen, a straight chain alkyl group, an arylgroup, or combinations thereof. More preferably, each R⁴ isindependently hydrogen or a straight chain alkyl group. Preferably, R⁴is hydrogen or an organic group that includes at least one carbon atom.Preferably, R⁴ is an organic group that includes no more than 100 carbonatoms, more preferably no more than 50 carbon atoms, even morepreferably no more than 20 carbon atoms, and most preferably no morethan 4 carbon atoms. Most preferably, R⁴ is hydrogen.

[0055] Preferably, the Y groups are OH or NH₂. More preferably, the Ygroups are both OH.

[0056] The polymers of the present invention can be prepared usingstandard techniques. Certain polymers can be made using one or more ofthe compounds of Formula I.

[0057] For example, if Y in Formula I is an amine (NR⁴H), one couldreact those amines with di-, tri- or poly(acids), di-, tri, or poly(acylchlorides), or with cyclic amides (lactams) to form poly(amides).Alternatively, one could react those amines with di-, tri- orpoly(anhydrides) to make poly(imides). Alternatively, one could reactthose amines with glycidyl-containing compounds to form epoxies.

[0058] If Y in Formula I is hydroxyl (OH), one could react thosehydroxyl groups with di-, tri-, or poly(acids), di-, tri-, or poly(acylchlorides), or with cyclic esters (lactones) to form poly(esters).Alternatively, one could react those hydroxyl groups with vinylether-containing compounds to make poly(acetals). Alternatively, onecould react those hydroxyls with sodium hydroxide to form sodium salts,and further react those salts with phosgene to form poly(carbonates).Reacting those sodium salts with other alkyl halide containing moietiescan lead to poly(sulfones) and poly(phosphates) and poly(phosphonates).

[0059] Typically, the preferred urethane- and/or urea-containingpolymers are made using polyisocyanates and one or more compounds ofFormula I. It should be understood, however, that diols or diamines thatdo not contain such silicon-containing moieties can also be used toprepare the urethane- and/or urea-containing polymers (particularly thesoft segments of the polymers) of the present invention, as long as theresultant polymer includes at least some silicon-containing moietieseither from diols or diamines or other reactants. Also, other polyolsand/or polyamines can be used, including polyester, polyether, andpolycarbonate polyols, for example, although such polyols are lesspreferred because they produce less biostable materials. Furthermore,the polyols and polyamines can be aliphatic (including cycloaliphatic)or aromatic, including heterocyclic compounds, or combinations thereof.

[0060] Examples of suitable polyols (typically diols) include thosecommercially available under the trade designation POLYMEG and otherpolyethers such as polyethylene glycol and polypropylene oxide,polybutadiene diol, dimer diol (e.g., that commercially available underthe trade designation DIMEROL (from Pripol 2033 from Unichema, NorthAmerica of Chicago, Ill.), polyester-based diols such as thosecommercially available as STEPANPOL (from Stepan Corp., Northfield,Ill.), CAPA (a polycaprolactone diol from Solvay, Warrington, Cheshire,United Kingdom), TERATE (from Kosa, Houston, Tex.), poly(ethyleneadipate) diol, poly(ethylene succinate) diol, poly(1,4-butanedioladipate) diol, poly(caprolactone) diol, poly(hexamethylene phthalate)diol, and poly(1,6-hexamethylene adipate) diol, as well aspolycarbonate-based diols such as poly(hexamethylene carbonate) diol.

[0061] Other polyols can be used as chain extenders in the preparationof polymers, as is conventionally done in the preparation ofpolyurethanes, for example. Chain extenders are used to provide hardsegments. Examples of suitable chain extenders include 1,10-decanediol,1,12-dodecanediol, 9-hydroxymethyl octadecanol, cyclohexane-1,4-diol,cyclohexane-1,4-bis(methanol), cyclohexane-1,2-bis(methanol), ethyleneglycol, diethylene glycol, 1,3-propylene glycol, dipropylene glycol,1,2-propylene glycol, trimethylene glycol, 1,2-butylene glycol,1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol,1,6-hexanediol, 1,2-hexylene glycol, 1,2-cyclohexaned iol,2-butene-1,4-d iol, 1,4-cyclohexanedimethanol,2,4-dimethyl-2,4-pentanediol, 2-methyl-2,4-pentaned iol,1,2,4-butanetriol, 2-ethyl-2-(hydroxymethyl)-1,3-propaned iol, glycerol,2-(hydroxymethyl)-1,3-propanediol, neopentyl glycol, pentaerythritol,and the like. Other chain extenders are described in InternationalPublication No. WO 99/03863.

[0062] Examples of suitable polyamines (typically diamines) includeethylenediamine, 1,4-diaminobutane, 1,10-diaminodecane,1,12-diaminododecane, 1,8-diaminooctane, 1,2-diaminopropane,1,3-diaminopropane, tris(2-aminoethyl)amine, lysine ethyl ester, and thelike.

[0063] Examples of suitable mixed alcohols/amines include5-amino-1-pentanol, 6-amino-1-hexanol, 4-amino-1-butanol,4-aminophenethyl alcohol, ethanolamine, and the like.

[0064] Suitable isocyanate-containing compounds for preparation ofpolyurethanes, polyureas, or polyurethanes-ureas, are typicallyaliphatic, cycloaliphatic, aromatic, and heterocyclic (or combinationsthereof) polyisocyanates. In addition to the isocyanate groups they caninclude other functional groups such as biuret, urea, allophanate,uretidine dione (i.e., isocyanate dimer), and isocyanurate, etc., thatare typically used in biomaterials. Suitable examples of polyisocyanatesinclude 4,4′-diisocyanatodiphenyl methane (MDI),4,4′-diisocyanatodicyclohexyl methane (HMDI),cyclohexane-1,4-diisocyanate, cyclohexane-1,2-diisocyanate, isophoronediisocyanate, tolylene diisocyanates, naphthylene diisocyanates,benzene-1,4-diisocyanate, xylene diisocyanates, trans-1,4-cyclohexylenediisocyanate, 1,4-diisocyanatobutane, 1,12-diisocyanatododecane,1,6-diisocyanatohexane, 1,5-diisocyanato-2-methylpentane,4,4′-methylenebis(cyclohexyl isocyanate),4,4′-methylenebis(2,6-diethyphenyl isocyanate), 4,4′-methylenebis(phenylisocyanate), 1,3-phenylene diisocyanate, poly((phenylisocyanate)-co-forma Idehyde), tolylene-2,4-diisocyanate,tolylene-2,6-diisocyanate, dimer diisocyanate, as well aspolyisocyanates available under the trade designations DESMODUR RC,DESMODUR RE, DESMODUR RFE, and DESMODUR RN from Bayer, and the like.

[0065] The relatively hard segments of the polymers of the presentinvention are preferably fabricated from short to medium chaindiisocyanates and short to medium chain diols or diamines, all of whichpreferably have molecular weights of less than about 1000 grams permole. Appropriate short to medium chain diols, diamines, anddiisocyanates include straight chain, branched, and cyclic aliphatics,although aromatics can also be used. Examples of diols and diaminesuseful in these more rigid segments include both the short and mediumchain diols or diamines discussed above.

[0066] In addition to the polymers described herein, biomaterials of theinvention can also include a variety of additives. These include,antioxidants, colorants, processing lubricants, stabilizers, imagingenhancers, fillers, and the like.

[0067] Starting Materials and Methods of Preparation

[0068] The compounds of Formula I above can be made by the syntheticroute described in the Examples Section. This typically involves thereaction of tetramethyldisiloxane (TMDS) and a hydrocarbon diene in aninert atmosphere using a catalyst such as platinum divinyl TMDS.Molecular weights can be targeted by the ratio of the two components(e.g., 3:2 TMDS to 1,7-octadiene would give approximately 620 Mn (numberaverage molecular weight) with hydride termination). A protectedhydroxyl or amine group can then be added through reaction of anotheralkene terminated molecule to the hydride end groups.Allyloxytrimethylsilane or allylaminotrimethysilane are examples ofprotected hydroxyl and amine that can be attached through the allylgroup to the hydride. The hydroxyl or amine is then deprotected. Waterwill deprotect the aminotrimethylsilane. Citric acid is one way todeprotect the oxytrimethylsilane.

[0069] The invention has been described with reference to variousspecific and preferred embodiments and will be further described byreference to the following detailed examples. It is understood, however,that there are many extensions, variations, and modification on thebasic theme of the present invention beyond that shown in the examplesand detailed description, which are within the spirit and scope of thepresent invention.

EXAMPLES

[0070] Materials: 10-Undecen-1-yl acetate was purchased from BedoukianResearch Incorporated (Danbury, Conn.). Hydrolsilylation catalyst(platinum(divinyltetramethyldisiloxane), containing 2-3% platinum inxylenes), 1,1,3,3-tetramethyldisiloxane (TMDS), and1,8-bis(chlorodimethyl)octane were purchased from United ChemicalTechnologies (Bristol, Pa.). 1,4-Butanediol was purchased fromMitsubishi Chemical America, Inc. (White Plains, N.Y.).4,4′-methylenebis(phenylisocyanate) (tradename Mondur M, flaked) waspurchased from Bayer Corporation (Pittsburgh, Pa.). The remainingreagents may be purchased from Aldrich Chemical Company, Incorporated(Milwaukee, Wis.).

Example 1 Synthesis of a Polyurethane/Urea from an AminotelechelicAlternating Siloxane-Hydrocarbon Polymer

[0071] Part 1: Synthesis of a 1500 Mn aminotelechelic alternatingsiloxane-hydrocarbon polymer.

[0072] A 3-neck round-bottomed flask was fitted with thermometer andadapter, magnetic stirring mechanism, water bath, cold-water condenser,pressure equalized addition funnel, glycerol bubbler and trap, andstopper. Nitrogen blanketing was used. 1,1,3,3-Tetramethyldisiloxane(TMDS) was added to the flask. In the addition funnel was placed1,7-octadiene. The molar ratio of TMDS to 1,7-octadiene was 7:6.Catalyst (platinum(divinyltetramethyldisiloxane)) was added dropwise atvarious points of the reaction as the 1,7-octadiene was added dropwise,being careful to control the exotherm of the reaction. The polymer washeated to 80° C. for an additional 1.5 hours.

[0073] A one-liter 3-neck round-bottomed flask was fitted withthermometer and adapter, magnetic stirring mechanism, heating unit,cold-water condenser, pressure equalized addition funnel, glycerolbubbler and trap, and stopper. Nitrogen blanketing was used.N-(Trimethylsilyl)allylamine (115.15 gm) was added to the flask. In theaddition funnel was placed 342.97 grams (gm) of the hydride terminateddisiloxane-hydrocarbon polymer synthesized above. The flask was heatedto 95° C., then the polymer was added over about one hour keeping thetemperature between 86° C. and 96° C. Next, water (55 milliliters (ml))and toluene (200 ml) were added to the flask. The water was separatedand the toluene solution washed again with water. The polymer wasfiltered through AMBERLITE IRC-718 ion exchange resin, rotaryevaporated, then dried in a vacuum oven.

[0074] Part 2: Synthesis of a polyurethane/urea using theaminotelechelic alternating disiloxane-hydrocarbon polymer of Part 1.

[0075] A 250-ml 3-neck round-bottomed flask was fitted with a Dean-Starktrap, condenser, nitrogen blanket, thermocouple, and stirring mechanism.A mixture of 20 ml N,N-dimethylacetamide (DMAC), 80 ml o-xylene and 20ml cyclohexane was heated in the flask until 20 ml of the mixture wasdistilled. The flask was cooled, sealed and transferred to an inertatmosphere glovebox. The solvent mixture was then heated to 50° C., and4,4′-methylenebis(phenylisocyanate) (MDI, 10.56 gm) was added to theflask. The aminotelechelic alternating disiloxane-hydrocarbon polymer ofPart 1 (37.84 gm) was placed in a syringe and transferred to the inertatmosphere glovebox. 1,4-Butanediol (1.85 gm) was also placed in asyringe and transferred to the inert atmosphere glovebox. Theaminotelechelic alternating disiloxane-hydrocarbon polymer of Part 1 wasadded to the flask over 20 minutes with the temperature of the mixturemaintained between 50° C. and 69° C. After the addition was complete,the flask temperature was stabilized at about 65° C. After another 20minutes, the 1,4-butanediol was added over 12 minutes with thetemperature rising to 69° C. The mixture was hazy, so additional DMACand xylene were added. After 90 ml DMAC and 40 ml xylene were added, themixture cleared somewhat. A drop of dibutyltin dilaurate catalyst wasadded. The temperature was raised to 90° C. to complete the reaction.There was a complete lack of isocyanate peak by infrared analysis at2272 cm⁻¹. Because an isocyanate-terminated polyurethane was desired,additional MDI (0.15 gm) was added. The polymer was precipitated byaddition to a mixture of acetone and water, filtered through boltingcloth and dried in a vacuum oven.

[0076] Properties of the polyurethane/urea. The dried polyurethane/ureawas solvent cast and heat pressed for testing of mechanical properties.The results are presented in Table 1. Tensile properties of the testspecimens were determined using an Instron Testing Machine withcrosshead speed of 12.7 centimeters per minute (cm/min) using a 22.67kilogram (kg) (50 pound) load cell.

[0077] To determine the molecular weights of the polymers, samples weredissolved in tetrahydrofuran and analyzed using an Alliance highperformance liquid chromatography system (Waters TechnologiesCorporation, Milford, Mass.). Phenomenex columns (HR4, 3, 1 and 0.5)were used (Phenomenex USA, Torrance, Calif.). Tetrahydrofuran was usedas the eluent at 0.28 milliliters per minute (ml/min) and 50° C. Themolecular weight values reported are relative to a polystyrene standardcurve. TABLE 1 Solvent cast Heat pressed Property polymer polymerHardness (Shore scale) 80 A Ultimate tensile 16.5 MPa (2400 psi) 9 MPa(1300 psi) Elongation at break 460% 410% Young's modulus 24.8 MPa (3600psi) 22.8 MPa (3300 psi) M_(n) 30800 g/mol 27000 g/mol M_(w) 113000g/mol 67300 g/mol

[0078] This data indicates that the solvent-cast polymer had bettertensile properties. The remaining properties are similar for the twopolymers.

Example 2 Synthesis of a Polyurethane/Urea from an AminotelechelicAlternating Siloxane-Hydrocarbon Polymer

[0079] Part 1: Synthesis of a 1500 Mn aminotelechelic alternatingdisiloxane-hydrocarbon polymer.

[0080] A 2000-ml 3-neck round-bottomed flask was fitted with thermometerand adapter, magnetic stirring mechanism, water bath, cold-watercondenser, pressure equalized addition funnel, glycerol bubbler andtrap, and stopper. Nitrogen blanketing was used.1,1,3,3-Tetramethyldisiloxane (393.97 gm) was added to the flask. In theaddition funnel was placed 1,5-hexadiene (206.51 gm). Catalyst(platinum(divinyltetramethyldisiloxane)) was added dropwise at variouspoints of the reaction as the diene was added dropwise, being careful tocontrol the exotherm of the reaction. The entire reaction took about 3hours, starting at room temperature and reaching a maximum of 76° C. Thepolymer was heated to 80° C. for additional time (about 1.5 hours).

[0081] A 1000-ml 3-neck round-bottomed flask was fitted with thermometerand adapter, magnetic stirring mechanism, heating unit, cold-watercondenser, pressure equalized addition funnel, glycerol bubbler andtrap, and stopper. Nitrogen blanketing was used.N-(Trimethylsilyl)allylamine (119.30 gm) was added to the flask. In theaddition funnel was placed a portion of the hydride terminatedsilicone-hydrocarbon from above (352.82 gm). The flask was heated to 95°C., then the polymer was added over about one-half hour keeping thetemperature between 88° C. and 95° C. Water was added (60 ml) andtoluene (200 ml). The water was separated and the toluene solutionwashed again with water. The polymer was filtered through a Whatman #2filter and AMBERLITE IRC-718 ion exchange resin, and then dried in avacuum oven.

[0082] Part 2: Synthesis of a polyurethane/urea from the aminotelechelicalternating disiloxane-hydrocarbon polymer of Part 1.

[0083] A 250-ml 3-neck round-bottomed flask was fitted with a Dean-Starktrap, condenser, and thermocouple. The reaction was run under nitrogenand stirred magnetically. A mixture of 50 ml N,N-dimethylacetamide, 50ml of o-xylene and 20 ml of cyclohexane was heated in the flask until 10ml of the mixture was distilled. The flask was cooled, sealed andtransferred to a glovebox. 4,4′-Methylenebis(phenylisocyanate) (MDI,11.47 gm) was added to the flask. The aminotelechelic alternatingdisiloxane-hydrocarbon polymer of Part 1 (37.05 gm) was placed in asyringe and transferred to a glovebox. 1,4-Butanediol was also placed ina syringe and transferred to the glovebox. The mixture was heated to 50°C. The aminotelechelic alternating disiloxane-hydrocarbon polymer ofPart 1 was added over 15 minutes with the temperature of the mixturekept between 50° C. and 66° C. After the addition was complete, thetemperature was maintained at about 65° C. After another 15 minutes, the1,4-butanediol was added over 5 minutes with the temperature rising to71° C. The mixture was hazy so additional DMAC was added. After theaddition of 58 ml DMAC, the mixture cleared considerably. A drop ofdibutyltin dilaurate catalyst was added. The temperature was brought to90° C. to complete the reaction. Infrared analysis was used to monitorthe isocyanate peak for judgement of completion of the reaction. Thepolymer was precipitated in acetone and water, filtered through boltingcloth and dried in a vacuum oven.

[0084] Properties of the polyurethane/urea. The dried polyurethane/ureawas heat pressed for testing of mechanical properties. The results arepresented in Table 2. Tensile properties of the test specimens weredetermined using an Instron Testing Machine with crosshead speed of 12.7cm per minute using a 22.67 kg (50 pound) load cell.

[0085] To determine the molecular weights of the polymers, samples weredissolved in tetrahydrofuran and analyzed using an Alliance highperformance liquid chromatography system (Waters TechnologiesCorporation, Milford, Mass.). Phenomenex columns (HR4, 3, 1 and 0.5)were used (Phenomenex USA, Torrance, Calif.). Tetrahydrofuran was usedas the eluent at 0.28 ml/min and 50° C. The molecular weight valuesreported are relative to a polystyrene standard curve. TABLE 2 PropertyHeat pressed polymer Hardness (Shore scale) 85 A Ultimate tensile 14.5MPa (2100 psi) Elongation at break 410% Young's modulus 40.7 MPa (5900psi) M_(n) 21500 g/mol M_(w) 50000 g/mol

Example 3 Synthesis of a 700 Mn Aminotelechelic AlternatingSiloxane-Hydrocarbon Polymer

[0086] A 3-neck round-bottomed flask was fitted with thermometer andadapter, magnetic stirring mechanism, water bath, cold-water condenser,pressure equalized addition funnel, balloon, and stopper. The system wasflushed with nitrogen before use. 1,1,3,3-Tetramethyldisiloxane (TMDS,202.1 gm) was added to the flask. In the addition funnel was placed1,5-hexadiene (82.06 gm). Catalyst(platinum(divinyltetramethyldisiloxane)) was added dropwise at variouspoints of the reaction as the diene was added dropwise, being careful tocontrol the exotherm of the reaction. The entire reaction took about 1.5hours, starting at room temperature and reaching a maximum of 59° C.

[0087] A 1000-ml 3-neck round-bottomed flask was fitted with thermometerand adapter, magnetic stirring mechanism, heating unit, cold-watercondenser, pressure equalized addition funnel, glycerol bubbler, heatingmantle, and stopper. The system was flushed with nitrogen during use.N-(Trimethylsilyl)allylamine (107 gm) was added to the flask. Also,toluene (200 ml) was added to the flask. In the addition funnel wasplaced a portion of the hydride-terminated disiloxane-hydrocarbonpolymer from above (178 gm). Catalyst (platinumdivinyltetramethyldisiloxane complex) was added intermitently. The flaskwas heated to 75° C., then the polymer was added over about one hourkeeping the temperature between 91° C. and 110° C. Water was added (27ml). The water was separated. The polymer was rotary evaporated thendried under vacuum.

Example 4 Preparation of a Polyurethane/Urea with a Soft SegmentComprising Alternating Disiloxane/Hydrocarbon Units

[0088] Fifty grams xylene, 50 grams N,N-dimethylacetamide (DMAC), and 40milliliters cyclohexane were added to a 3-neck 500-milliliterround-bottomed flask. The flask was outfitted with a Dean-Stark trap, astirrer powered by an air motor, and a thermocouple. A condenser wasconnected to the Dean-Stark trap, and an adapter connected to a nitrogensource and bubbler was connected to the condenser. Stirring wasinitiated and the contents of the flask were heated to 110° C. Ninemilliliters of cyclohexane were distilled from the flask. The flask wascooled to 50° C. and the entire apparatus was transferred to anitrogen-purged glovebox. Then 19.36 grams of flaked MDI were added tothe flask. The Dean-Stark trap was then removed and replace with acondenser attached to a drying tube. The mixture in the flask wasstirred and 27.61 grams of the aminotelechelic alternatingdisiloxane-hydrocarbon polymer synthesized in Example 3 was added overten minutes using a syringe. The rate of addition was controlled inorder to keep the contents of the flask at a temperature of less than50° C. The maximum temperature of the flask during the addition was49.6° C. Stirring was continued for twenty minutes, then 3.40 grams of1,4-butanediol was added in one bolus from a 5-cc (cubic centimeter)syringe. The reaction temperature increased from 44° C. to 51° C. overapproximately 10 minutes following the addition. After 30 minutes, thepolymer had gelled. One hundred grams of DMAC were added to the reactionmixture and it was heated to 110° C., which dissolved the gel. After anadditional 30 minutes, there was no isocyanate present by infraredspectroscopy at an absorbance at 2272 cm⁻¹. About one gram of additionalMDI was added to the reaction flask, and after ten minutes, the productwas examined by infrared spectroscopy, which showed no band due toisocyanate. Three more small additions of MDI were made, bringing theamount of MDI in the polymer formulation to a total of 21.52 grams.After the addition of a total of four additions of MDI, a residualisocyanate band was observed by infrared spectroscopy. To bring theisocyanate band to the desired level, an additional 0.25 grams of1,4-butanediol was added, bringing the total 1,4-butanediol in theformulation to 3.65 grams. An initial attempt to precipitate the polymerby pouring the solution into a Waring blender containing stirredisopropanol was unsuccessful. The polymer was successfully precipitatedby pouring the combined DMAC/isopropanol solution into a Waring blendercontaining stirred acetone. The polymer was then dried overnight in avacuum oven at 100° C. A portion of the polymer was dissolved inN-methylpyrrolidone and cast into a film. This polymer film was found tohave the properties listed in the table below: TABLE 3 Properties ofpolyurethane/urea Property Hardness (Shore scale) 65 D Ultimate tensilestrength 21.4 MPa (3100 psi) Elongation at break 93% Young's modulus 244MPa (35400 psi)

Example 5 Preparation of a Polyurethane/Urea with a Soft SegmentComprising Alternating Disiloxane/Hydrocarbon Units

[0089] One hundred milliliters of toluene, 100 millilitersN,N-dimethylacetamide (DMAC), and 25 milliliters cyclohexane were addedto a 3-neck 500-milliliter round-bottomed flask. The flask was outfittedwith a Dean-Stark trap, a stirrer powered by an air motor, and athermocouple. A condenser was connected to the Dean-Stark trap, and anadapter connected to a nitrogen source and bubbler was connected to thecondenser. Stirring was initiated and the contents of the flask wereheated to 110° C. for two hours. Seven milliliters of cyclohexane weredistilled from the flask. The flask was cooled to 50° C. and the entireapparatus was transferred to a nitrogen-purged glovebox. Then 15.94grams of flaked MDI were added to the flask. The Dean-Stark trap wasthen removed and replace with a condenser attached to a drying tube. Themixture in the flask was stirred and 30.82 grams of aminotelechelicalternating disiloxane-hydrocarbon polymer was added over five minutesusing a syringe, then an additional 2.72 grams of aminotelechelicalternating disiloxane-hydrocarbon polymer synthesized in Example 3 wasadded over five minutes using a syringe. The maximum temperature of theflask during the addition was 51° C. Stirring was continued for fifteenminutes at 50° C., then 0.84 grams of 1,4-butanediol was added in onebolus from a 5 cc syringe. After three minutes, two drops of stannousoctonate catalyst was added, causing an exotherm that reached 54° C.after one minute. After 30 minutes, there was a large isocyanate band inthe infrared spectrum. Several portions of the aminotelechelic polymerwere added to the reaction mixture, totaling 4.72 grams, but theseadditions did not change the isocyanate band. It was then assumed thatthe polymer being formed had poor solubility in the solvent mixture. Themixture was then heated to 70° C., at which point the solution startedto bubble. After one minute at this temperature, the mixture thickenedand gelled. One hundred additional grams of DMAC were added and themixture was heated to 110° C. There was no isocyanate band observed atthis point, so an additional 0.99 grams MDI was added to the reactionmixture. After the band due to isocyanate had stabilized, the polymerwas precipitated in a mixture of isopropanol and water, extracted withacetone, and then dried in a vacuum oven at 100° C. overnight. A portionof the polymer was then redissolved in N-methylpyrrolidone and cast intoa film. This polymer film was found to have the properties list in thetable below: TABLE 4 Properties of polyurethane/urea Property Ultimatetensile strength 33.1 MPa (4800 psi) Elongation at break 250% Young'smodulus 275 MPa (39900 psi)

Example 6 Synthesis of a Hydroxytelechelic AlternatingDisiloxane-Hydrocarbon Polymer

[0090] A 3-necked round-bottomed flask was fitted with thermometer andadapter, magnetic stirring mechanism, water bath, cold-water condenser,pressure equalized addition funnel, balloon, and stopper. The system wasflushed with nitrogen before use. 1,1,3,3-Tetramethyldisiloxane (TMDS,68.0 gm) was added to the flask. In the addition funnel was placed1,7-octadiene (34.0 gm). Catalyst(platinum(divinyltetramethyldisiloxane)) was added dropwise at variouspoints of the reaction as the diene was added dropwise, being careful tocontrol the exotherm of the reaction. The entire reaction took about 1hour, starting at room temperature and reaching a maximum of 75° C.Allyloxytrimethylsilane (64.73 gm, AOTMS) was added to the additionfunnel. It was added dropwise over about 1 hour with occasional additionof catalyst. Reaction temperature ranged from 30-43° C. Citric acid(0.0570 gm) and methanol (50 ml) were added to the AOTMS terminatedpolymer (5.32 gm) in hexane (50 ml) in a 250-ml beaker. The solution waswashed with deionized water and the solvent removed using a rotaryevaporator.

Example 7 Preparation of a Hydroxytelechelic AlternatingDisiloxane-Hydrocarbon Polymer

[0091] Part 1: Synthesis of 1-acetoxy-11-chlorodimethylsilylundecane.

[0092] To a three-liter four-neck round-bottomed flask was charged 1090grams of 10-undecen-1-yl acetate and 40 drops of(platinum(divinyltetramethyldisiloxane) catalyst solution (2-3% platinumin xylenes). To this mixture was slowly added 425 grams ofchlorodimethylsilane from a one-liter addition funnel. The addition tookplace over 165 minutes, at such a rate to prevent an excessive exotherm.After the initial exotherm, the addition rate was controlled to maintainthe temperature of the reaction mixture at about 70° C. A heating mantlewas placed under the flask and the reaction mixture was maintained at34° C. overnight. The crude product was distilled under vacuum directlyfrom the reaction flask, using a distillation column 1.5 cm in diameterand 22 cm in length. The column was packed with stainless steel mesh. Onthis column was placed a distillation head and a coldfinger. The maincut distilled at about 1 millitorr (0.133 Pa) and 122-125° C. An aliquotwas submitted for gas chromatographic analysis to determine purity.

[0093] Part 2: Synthesis of an acetoxytelechelic alternatingdisiloxane-hydrocarbon polymer.

[0094] Prior to the reaction, 1,8-bis(chlorodimethyl)octane wasdistilled under high vacuum (<1 millitorr (0.133 Pa)). The fractionsthat distilled at about 96° C. were used. The1-acetoxy-11-chlorodimethylsilylundecane synthesized above (739 grams)and 1,8-bis(chlorodimethylsilyl)octane (663 grams) were combined withone liter of hexanes in a five-liter round-bottomed flask. To this wasadded 1.38 liters of deionized water. The mixture was stirredmagnetically using a poly(tetrafluoroethylene) stirbar. There was a mildexotherm, which peaked at a mixture temperature of 44° C. The mixturewas stirred for six days at room temperature. Then the water layer waspumped off the reaction mixture through a glass drop tube using aperistaltic pump. The organic layer was washed twice with a solution of100 grams sodium carbonate in 1800 milliliters of water. During bothwashes, the mixture was stirred vigorously for 30 minutes. Then, theorganic phase was washed with 1800 milliliters of deionized water for4-5 times, until the wash water was found to be of neutral pH whentested with pH paper. The organic phase was dried using magnesiumsulfate and the hexanes removed using a rotary evaporator.

[0095] Part 3: Deprotection of the acetoxytelechelic alternatingdisiloxane-hydrocarbon polymer to yield a hydroxytelechelic alternatingdisiloxane-hydrocarbon polymer.

[0096] The aceotoxytelechelic alternating disiloxane-hydrocarbon polymerprepared in Part 2 (1234 grams) was placed in a twelve-literround-bottomed flask with 2.2 liters tetrahydrofuran and 1.9 liters ofethanol. The flask was outfitted with a condenser and the mixture washeated to reflux in the presence of poly(tetrafluoroethylene) boilingchips. Sixty grams of potassium cyanide was weighed into a400-milliliter beaker and 220 milliliters of deionized water was added.After the potassium cyanide had completely dissolved, the solution wasadded to the flask over about ten minutes. The reaction was refluxed andturned from a slightly cloudy yellow solution to a clear solution withan orange cast. The pot temperature was 68° C. Analysis by infraredspectroscopy indicated that the product was approximately 44%deprotected. The solvents were removed from the reaction mixture using arotary evaporator, the crude polymer was redissolved in ethyl ether, andthen the crude product was washed four times with water. The washing wasperformed using a six-liter separatory funnel and each water wash wasapproximately 1.5 liters. The deprotection step was repeated on thepartially deprotected polymer, with the exception that seventy grams ofpotassium cyanide was used, and the time that the reaction mixture wasrefluxed was increased to one week.

[0097] Additional purification of the hydroxytelechelic alternatingdisiloxane-hydrocarbon polymer was performed by dissolving the polymerat 50% solids in a 1/1 blend of ether/hexanes. Deionized water washes(1500 ml/wash) were repeated in a 6-liter separatory funnel until theywere of neutral pH. Residual water was removed by two treatments of theorganic phase with anhydrous magnesium sulfate. After filtration, thesolvents were removed by rotary evaporation at 40° C. at 0.1 mm vacuum.The resultant polymer (965.6 grams) was an orange liquid and wasdetermined to be 99.4% deprotected by proton NMR.

[0098] The purification procedure was continued by adding an equalvolume of anhydrous tetrahydrofuran (Aldrich) to the polymer. Thediluted product was passed through an 8.9 cm (3.5 inch) diameter columnconstructed with layers of glass wool, washed silica sand and 6.4 cm(2.5 inch) of Brockmann 1, neutral, activated alumina (Aldrich). Afterisolating the first filtrate, the column was rinsed with one liter offresh tetrahydrofuran. Both of these light-yellow filtrates wereprocessed separately.

[0099] The final purification step was a filtration of each filtrategenerated in the previous step through a column of Silica gel (Grade 22)covered with an equal quantity of Brockmann 1, neutral, activatedalumina. After the polymer solution eluted, the column was rinsed withone liter of fresh tetrahydrofuran. The resultant filtrates were clearand almost colorless. Solvent was removed from each filtrate by rotaryevaporation under oil pump vacuum at 40° C. The first filtrate, 517grams, had a hydroxyl equivalent weight of 520.7 grams/equivalent. Thesecond filtrate, 404 grams, had a hydroxyl equivalent weight of 452.8.The combined yields of the two purified hydroxytelechelic alternatingdisiloxane-hydrocarbon polymer was 96.4% of the starting deprotectedhydroxytelechelic alternating d isiloxane-hydrocarbon polymer.

Example 8 Synthesis of a Polyurethane Containing an AlternatingDisiloxane-Hydrocarbon Soft Segment Utilizing a One-Step SolutionPolymerization Process

[0100] To a flame-dried, 1-liter, three-neck, round-bottomed flask,82.95 grams (0.1832 equivalents) hydroxytelechelic alternatingdisiloxane-hydrocarbon polymer of the previous example and 6.35 grams(0.1411 equivalents) 1,4-butanediol were added. The flask was equippedwith air-driven mechanical stirrer with stirrer bearing, a thermocouplewith temperature controller, a nitrogen inlet and a nitrogen outletcapped with a mineral oil bubbler to maintain a closed system atatmospheric pressure. All additions took place in a nitrogen-purgedglovebox. Anhydrous 1,4-dioxane (Aldrich, 400 grams) was added to make aclear, low-viscosity solution. A slight nitrogen purge was introducedinto the headspace of the flask while the stirred contents were heatedto 90° C. When the reaction mixture reached this temperature, 41.92grams (0.3340 equivalents) of solid, flaked MDI (fused Mondur M, BayerCorporation) was added. The reaction mixture exotherm reached 98° C.After the exotherm was complete, the reaction mixture was maintained at90° C. Infrared analysis of the polymer solution determined that thereaction was progressing slowly as shown by FTIR analysis, whichindicated a significant isocyanate absorbance at 2270 cm⁻¹. After 5.5hours, two drops of tin(II) 2-ethylhexanoate catalyst (Aldrich) wasadded to increase the rate of polymerization. Following the catalystaddition, the viscosity increased very rapidly and additional anhydrousdioxane was added to reduce the solids content from 25 to 20 percent inorder to lower the viscosity. Infrared analysis revealed the reactionwas complete and a relatively weak band due to residual isocyanate wasdetected using FTIR. This was expected by the reaction stoichiometry,which was calculated to produce an isocyanate-terminated polyurethane.The viscous dioxane/polymer solution was poured into isopropanol as itwas rapidly stirred in a 1.2 liter glass container by a variable speed,explosion proof laboratory blender. The result was a homogeneous,viscous polymer solution with a one to two blend of dioxane/isopropanol.Deionized water was slowly added to precipitate the polymer as a coarsepowder. The solidified polymer was filtered from the solvent andreturned to the blender assembly twice to be blended, washed andfiltered with methanol to selectively remove the majority of thedioxane. The resultant polymer was dried in a vacuum oven for 60 hoursat 50° C. followed by 24 hours at 80° C. The white powder wascompression molded at 210° C. with a Carver press into clear 0.635 mm(25 mil) films. After annealing at 70° C. for 24 hours, mechanicalproperties were measured with an MTS Sintech I/D using ASTM D638-5method, with extensometer. Results were as follows: Ultimate TensileStrength=30.2 MPa (4378 psi), Elongation at break=606% and Young'sModulus=57.9 MPa (8399 psi). Infrared analysis detected absorbencies at3327, 2964, 2915, 2847, 1713, 1695, 1596, 1540, 1525, 1466, 1412, 1312,1257, 1237, 1063, 1045, 844, and 795 cm⁻¹.

Example 9 Synthesis of a Polyurethane Containing an AlternatingDisiloxane-Hydrocarbon Soft Segment Utilizing a One-Step, Solvent-FreePolymerization Process

[0101] Synthesis was completed in a nitrogen-purged glovebox utilizingthe same lots of reactants as in Example 8. In a 250 ml polypropylenebeaker, 82.96 grams (0.1832 equivalents) hydroxytelechelic alternatingdisiloxane-hydrocarbon polymer was blended with 6.36 grams (0.1411equivalents) of 1,4-butanediol. The homogenous diol blend was heated to100° C. in an oven located in a nitrogen-purged glovebox. Next, 40.95grams (0.3259 equivalents) of clear, precipitate free, molten MDI wasadded. The clear, low viscosity blend was stirred rapidly with apolypropylene stir stick in the absence of any catalyst. After 30seconds, the blend became opaque and viscosity rapidly increased. After60 seconds, the partially reacted polymer was too viscous to stir. Thestirrer stick was removed and the reaction was further heated in theglovebox oven for 18 hours at 100° C. After cooling to room temperature,the beaker was removed and the solid polymer was cut into pieces with aband saw. Polymer films were compression molded at 210° C. with a Carverpress into slightly hazy 0.635 mm (25 mil) films. After annealing at 70°C. for 24 hours, mechanical properties were measured using ASTM D638-5method, with a MTS Sintech I/D with extensometer. Results were asfollows: Ultimate Tensile Strength=26.3 MPa (3418 psi), Elongation atbreak=610% and Young's Modulus=57.8 MPa (8389 psi). Infrared analysis ofa 0.08 mm (3 mil) thick, molded film detected a very small level ofresidual isocyanate at 2270 cm⁻¹, as expected from the reactionstoichiometry. In general, the infrared spectrum had the same spectralfeatures as the solution-polymerized polymer of Example 8.

Example 10 Synthesis of a Polyurethane Containing an AlternatingDisiloxane-Hydrocarbon Soft Segment Utilizing a Two-Step, Solvent-FreePolymerization

[0102] This polymer was made with the same reactants as in Examples 8and 9. In a nitrogen purged dry box, 12.77 grams (0.02823 equivalents)hydroxytelechelic alternating disiloxane-hydrocarbon polymer waspreheated in a 250 ml polypropylene beaker to 100° C. in the dry boxoven before 6.32 grams (0.05036 equivalents) of solid, flaked MDI wasadded. The reactants were rapidly stirred with a polypropylene stirstick to form a clear, low viscosity solution before returning thebeaker to the 100° C. oven. After 10 minutes, the isocyanate-terminatedprepolymer was a clear, medium viscosity blend. After 30 minutes, therewas no further increase in viscosity. In the absence of any catalyst,0.98 grams (0.02178 equivalents) of 1,4-butanediol was added. Afterstirring for 2 minutes, the medium viscosity blend went from clear tohazy. After 4 minutes, the blend was too viscous to stir and reactionblend was heated for 18 hours at 100° C. in the dry box oven to completethe reaction. After cooling to room temperature, the beaker was removedand the solid polymer was cut into pieces with a band saw. Polymer filmswere compression molded at 220° C. in a Carver press into 0.635 mm (25mil) films. After annealing for 24 hours at 70° C., mechanicalproperties were measured using ASTM D638-5 method with an MTS SintechI/D with extensometer. Results were as follows: Ultimate TensileStrength=23.9 MPA (3468 psi), Elongation at break=560%, Young'sModulus=53.3 MPa (7736 psi). Gel Permeation Chromatography (GPC)molecular weight in tetrahydrofuran utilizing polystyrene standardsdetermined that Mw=101,000, Mn=42,300, polydispersivity=2.40.Differential Scanning Calorimeter (DSC) was used to determine T_(g)=−73°C., T_(m)=83, 137& 166° C. and T_(c)=47° C. FTIR spectrum of a 0.08 mm(3 mil) thick molded film had the same spectral features as thepolyurethanes described in Examples 8 and 9. The polymer had a residualisocyanate band detected at 2270 cm⁻¹, as expected by the reactionstoichiometry.

Example 11 Stability Testing

[0103] The chemical stability of the polyurethanes synthesized inExamples 8 and 9 were compared to polyurethane and silicone polymersthat are standards of the medical industry for use in long-term implantapplications, such as pacemaker leads. In the Tables below, PELLETHANE80A refers to PELLETHANE-2363-80A, a polyether polyurethane sold by theDow Chemical Company, Midland, Mich.; ELASTHANE 55D is a polyetherpolyurethane sold by Polymer Technologies Group, Berkeley, Calif.; andthe silicones MED-4516 and MED-4719 are sold by Nusil Technology,Carpinteria, Calif. Polymer specimens were soaked in various solutionsto test their oxidative and hydrolytic stability. The solutions usedinclude 1 N aqueous sodium hydroxide, 1 N aqueous hydrochloric acid, 1 Msilver nitrate, and 1 M ferric chloride. The polymers were molded into0.635 mm (25 mil) thick films and cut into test specimens with a dieaccording to ASTM D638-5. Test specimens were stored at 70° C. for 4 and8 weeks in each of these solutions. For each test point, 5-8 specimenswere added to each 100-ml (four-ounce) jar of solution. Tensileproperties of the test specimens were determined using a MTS Sintech 1/Dtensile tester with extensometer with a crosshead speed of 12.7 cm perminute using a 22.67 kg (50 pound) load cell. Retention of physicalproperties was determined by comparison of the tensile properties of thetest specimens to the tensile properties of identical specimens storedat ambient laboratory conditions. This comparison is reported as apercentage in the Tables as “percentage of properties retained”. Thespecimens were tested both wet and dry. A “wet” specimen is one removedfrom the test solution, rinsed with deionized water, blotted dry, andtested immediately. A “dry” specimen is tested after rinsing withdeionized water, drying to a constant weight in a vacuum oven, and thenallowing the moisture level of the specimen to equilibrate to ambientlaboratory conditions. In these Tables, “UTS” refers to ultimate tensilestrength and % E refers to percent elongation. TABLE 5 PELLETHANE 80A -Percentage of properties retained 4 Weeks (Wet) 8 Weeks (wet) 8 Weeks(Dry) Conditions UTS % E UTS % E UTS % E NaOH 91 113 94 120 115 120 HCl74 97 69 108 94 115 FeCl₃ 68 128 40 119 48 105 AgNO₃ 23 99 30 117 46 108

[0104] TABLE 6 ELASTHANE 55D - Percentage of properties retained 4 Weeks(Wet) 8 Weeks (wet) 8 Weeks (Dry) Conditions UTS % E UTS % E UTS % ENaOH 95 114 101 123 117 126 HCl 90 106 82 115 99 118 FeCl₃ 83 118 64 11469 88 AgNO₃ 57 104 29 83 41 80

[0105] TABLE 7 Polymer of Example 8 - Percentage of properties retained4 Weeks (Wet) 8 Weeks (wet) 8 Weeks (Dry) Conditions UTS % E UTS % E UTS% E NaOH 75 106 65 99 79 101 HCl 74 119 59 117 77 124 FeCl₃ 74 106 70117 84 114 AgNO₃ 69 97 57 89 67 93

[0106] TABLE 8 Polymer of Example 9 - Percentage of properties retained4 Weeks (Wet) 8 Weeks (wet) 8 Weeks (Dry) Conditions UTS % E UTS % E UTS% E NaOH 75 90 66 93 71 86 HCl 68 110 61 109 81 121 FeCl₃ 73 106 64 10783 119 AgNO₃ 70 90 63 89 73 89

[0107] TABLE 9 3/30 MED-4516 Silicone Elastomer - Percentage ofproperties retained 4 Weeks (Wet) 8 Weeks (wet) 8 Weeks (Dry) ConditionsUTS % E UTS % E UTS % E NaOH 93 79 97 76 99 78 HCl 43 49 38 38 44 38FeCl₃ 83 84 70 67 71 70 AgNO₃ 91 84 89 84 86 76

[0108] TABLE 10 MED-4719 Silicone Elastomer - Percentage of propertiesretained 4 Weeks (Wet) 8 Weeks (wet) 8 Weeks (Dry) Conditions UTS % EUTS % E UTS % E NaOH 118 73 107 114 126 68 HCl 28 42 23 26 25 23 FeCl₃46 52 33 42 38 44 AgNO₃ 111 78 103 125 105 72

[0109] It can be seen from the data presented in Tables 5-10 that thepolyether polyurethanes (Tables 5 and 6) are more susceptible tooxidative degradation than the polymers of the present invention (Tables7 and 8). It can also be seen from the data above that the silicones(Tables 9 and 10) are more susceptible to acidic and basic hydrolysisthan the polymers of the present invention. It has thus beendemonstrated that the polymers of the present invention have greaterresistance to oxidative attack than the polyurethanes commonly used tofabricate medical devices, and that the polymers of the presentinvention have greater resistance to hydrolysis than the siliconescommonly used to fabricate medical devices. Thus, the polymers of thepresent invention have a combined resistance to oxidative and hydrolyticattack that is not found in the polymers currently used to fabricatemedical devices intended for long-term implant applications.

[0110] The complete disclosures of the patents, patent documents, andpublications cited herein are incorporated by reference in theirentirety as if each were individually incorporated. Variousmodifications and alterations to this invention will become apparent tothose skilled in the art without departing from the scope and spirit ofthis invention. It should be understood that this invention is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the inventionintended to be limited only by the claims set forth herein as follows.

What is claimed is:
 1. A polymer comprising one or moresilicon-containing groups, wherein the polymer is derived from acompound of the formula: Y—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—Y wherein:each Y is independently OH or NR⁴H; n=2 or more; each R¹ isindependently a straight chain or branched alkylene group optionallyincluding heteroatoms; each R² is independently a saturated orunsaturated aliphatic group, an aromatic group, or combinations thereof,optionally including heteroatoms; Z is oxygen or R³, wherein each R³ isindependently a straight chain alkylene group, a phenylene group, or astraight chain or branched alkyl substituted phenylene group, whereineach R³ optionally includes heteroatoms; and each R⁴ is independently Hor a saturated or unsaturated aliphatic group, an aromatic group, orcombinations thereof; with the proviso that at least one of the Z groupsis oxygen and at least one of the Z groups is R³; and with the provisothat R¹ does not include urethane groups when Y is OH.
 2. The polymer ofclaim 1 comprising urethane linkages.
 3. The polymer of claim 1 whereinn=2 to
 50. 4. The polymer of claim 1 wherein each R¹ is independently astraight chain or branched (C3-C20)alkylene group.
 5. The polymer ofclaim 1 wherein Y is NH₂.
 6. The polymer of claim 1 wherein each R² isindependently a straight chain or branched (C1-C20)alkyl group.
 7. Thepolymer of claim 6 wherein each R² is independently a straight chain orbranched (C1-C3)alkyl group.
 8. The polymer of claim 1 wherein each R²is independently a phenyl group or a straight chain or branched(C1-C20)alkyl substituted phenyl group.
 9. The polymer of claim 8wherein each R² is independently a phenyl group or a straight chain orbranched (C1-C6)alkyl substituted phenyl group.
 10. The polymer of claim1 wherein each R³ is independently a straight chain (C1-C20)alkylenegroup.
 11. The polymer of claim 10 wherein each R³ is independently astraight chain (C4-C12)alkylene group.
 12. The polymer of claim 11wherein each R³ is independently a straight chain (C6-C10)alkylenegroup.
 13. The polymer of claim 1 wherein each R³ is independently aphenylene group or a straight chain or branched (C1-C20)alkylsubstituted phenylene group.
 14. The polymer of claim 1 wherein each R³is independently a phenylene group or a straight chain or branched(C1-C6)alkyl substituted phenylene group.
 15. The polymer of claim 1wherein each Y is OH.
 16. The polymer of claim 1 wherein each R⁴ isindependently H or a straight chain alkyl group.
 17. The polymer ofclaim 1 which is a segmented polyurethane.
 18. The polymer of claim 1which is a biomaterial.
 19. The polymer of claim 1 which issubstantially free of ether, ester, and carbonate linkages.
 20. Thepolymer of claim 1 which is linear, branched, or crosslinked.
 21. Thepolymer of claim 1 wherein every other Z is oxygen.
 22. The polymer ofclaim 1 further comprising one or more soft segments derived from a diolthat does not contain a silicon-containing group.
 23. The polymer ofclaim 1 further comprising one or more hard segments derived from achain extender.
 24. A medical device comprising a polymer comprising oneor more silicon-containing groups, wherein the polymer is derived from acompound of the formula: Y—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—Y wherein:each Y is independently OH or NR⁴H n=2 or more; each R¹ is independentlya straight chain or branched alkylene group optionally includingheteroatoms; each R² is independently a saturated or unsaturatedaliphatic group, an aromatic group, or combinations thereof, optionallyincluding heteroatoms; Z is oxygen or R³, wherein each R³ isindependently a straight chain alkylene group, a phenylene group, or astraight chain or branched alkyl substituted phenylene group, whereineach R³ optionally includes heteroatoms; and each R⁴ is independently Hor a saturated or unsaturated aliphatic group, an aromatic group, orcombinations thereof; with the proviso that at least one of the Z groupsis oxygen and at least one of the Z is R³; and with the proviso that R¹does not include urethane groups when Y is OH.
 25. The medical device ofclaim 24 wherein the polymer comprises urethane linkages.
 26. Themedical device of claim 24 wherein n=2 to
 50. 27. The medical device ofclaim 24 wherein each R¹ is independently a straight chain or branched(C3-C20)alkylene group.
 28. The medical device of claim 24 wherein Y isNH₂.
 29. The medical device of claim 24 wherein each R² is independentlya straight chain or branched (C1-C20)alkyl group.
 30. The medical deviceof claim 29 wherein each R² is independently a straight chain orbranched (C1-C3)alkyl group.
 31. The medical device of claim 24 whereineach R² is independently a phenyl group or a straight chain or branched(C1-C20)alkyl substituted phenyl group.
 32. The medical device of claim31 wherein each R² is independently a phenyl group or a straight chainor branched (C1-C6)alkyl substituted phenyl group.
 33. The medicaldevice of claim 24 wherein each R³ is independently a straight chain(C1-C20)alkylene group.
 34. The medical device of claim 33 wherein eachR³ is independently a straight chain (C4-C12)alkylene group.
 35. Themedical device of claim 34 wherein each R³ is independently a straightchain (C6-C10)alkylene group.
 36. The medical device of claim 24 whereineach R³ is independently a phenylene group or a straight chain orbranched (C1-C20)alkyl substituted phenylene group.
 37. The medicaldevice of claim 36 wherein each R³ is independently a phenylene group ora straight chain or branched (C1-C6)alkyl substituted phenylene group.38. The medical device of claim 24 wherein each Y is OH.
 39. The medicaldevice of claim 24 wherein each R⁴ is independently H or a straightchain alkyl group.
 40. The medical device of claim 24 wherein thepolymer is a segmented polyurethane.
 41. The medical device of claim 24wherein the polymer is a biomaterial.
 42. The medical device of claim 24wherein the polymer is substantially free of ether, ester, and carbonatelinkages.
 43. The medical device of claim 24 wherein the polymer islinear, branched, or crosslinked.
 44. The medical device of claim 24wherein every other Z is oxygen.
 45. The medical device of claim 24wherein the polymer further comprises one or more soft segments derivedfrom a diol that does not contain a silicon-containing group.
 46. Themedical device of claim 24 wherein the polymer further comprises one ormore hard segments derived from a chain extender.
 47. A polymercomprising one or more silicon-containing groups, wherein the polymercomprises a group of the formula:—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—wherein: n=2 or more; each R¹ isindependently a straight chain or branched alkylene group optionallyincluding heteroatoms; each R² is independently a saturated orunsaturated aliphatic group, an aromatic group, or combinations thereof,optionally including heteroatoms; Z is oxygen or R³, wherein each R³ isindependently a straight chain alkylene group, a phenylene group, or astraight chain or branched alkyl substituted phenylene group, whereineach R³ optionally includes heteroatoms; and each R⁴ is independently Hor a saturated or unsaturated aliphatic group, an aromatic group, orcombinations thereof; with the proviso that at least one of the Z groupsis oxygen and at least one of the Z groups is R³; and with the provisothat R¹ does not include urethane groups.
 48. A medical devicecomprising a polymer comprising one or more silicon-containing groups,wherein the polymer comprises a group of the formula:—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—wherein: n=2 or more; each R¹ isindependently a straight chain or branched alkylene group optionallyincluding heteroatoms; each R² is independently a saturated orunsaturated aliphatic group, an aromatic group, or combinations thereof,optionally including heteroatoms; Z is oxygen or R³, wherein each R³ isindependently a straight chain alkylene group, a phenylene group, or astraight chain or branched alkyl substituted phenylene group, whereineach R³ optionally includes heteroatoms; and each R⁴ is independently Hor a saturated or unsaturated aliphatic group, an aromatic group, orcombinations thereof; with the proviso that at least one of the Z groupsis oxygen and at least one of the Z groups is R³; and with the provisothat R¹ does not include urethane groups.
 49. A compound comprising oneor more silicon-containing groups, wherein the compound is of theformula: Y—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—Y wherein: each Y isindependently OH or NR⁴H; n=2 or more; each R¹ is independently astraight chain or branched alkylene group optionally includingheteroatoms; each R² is independently a saturated or unsaturatedaliphatic group, an aromatic group, or combinations thereof, optionallyincluding heteroatoms; Z is oxygen or R³, wherein each R³ isindependently a straight chain alkylene group, a phenylene group, or astraight chain or branched alkyl substituted phenylene group, whereineach R³ optionally includes heteroatoms; and each R⁴ is independently Hor a saturated or unsaturated aliphatic group, an aromatic group, orcombinations thereof; with the proviso that at least one of the Z groupsis oxygen and at least one of the Z groups is R³; and with the provisothat R¹ does not include urethane groups when Y is OH.
 50. The polymerof claim 49 wherein each R¹ is independently a straight chain orbranched (C3-C20)alkylene group.
 51. The polymer of claim 49 whereineach R² is independently a straight chain or branched (C1-C20)alkylgroup.
 52. The polymer of claim 49 wherein each R² is independently aphenyl group or a straight chain or branched (C1-C20)alkyl substitutedphenyl group.
 53. The polymer of claim 49 wherein each R³ isindependently a straight chain (C1-C20)alkylene group.
 54. The polymerof claim 49 wherein each R³ is independently a phenylene group or astraight chain or branched (C1-C20)alkyl substituted phenylene group.55. A method of making a segmented polymer, the method comprising:combining a polyisocyanate with a compound of the formula:Y—R¹—Si(R²)₂—[-Z-Si(R²)₂—]_(n)—R¹—Y wherein: each Y is independently OHor NR⁴H; n=2 or more; each R¹ is independently a straight chain orbranched alkylene group optionally including heteroatoms; each R² isindependently a saturated or unsaturated aliphatic group, an aromaticgroup, or combinations thereof, optionally including heteroatoms; Z isoxygen or R³, wherein each R³ is independently a straight chain alkylenegroup, a phenylene group, or a straight chain or branched alkylsubstituted phenylene group, wherein each R³ optionally includesheteroatoms; and each R⁴ is independently H or a saturated orunsaturated aliphatic group, an aromatic group, or combinations thereof;with the proviso that at least one of the Z groups is oxygen and atleast one of the Z groups is R³; and with the proviso that R¹ does notinclude urethane groups when Y is OH.